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论文类型： 期刊论文

发表时间： 2012-03-07

发表刊物： JOURNAL OF PHYSICS-CONDENSED MATTER

收录刊物： SCIE、EI、PubMed、Scopus

卷号： 24

期号： 9

页面范围： 095004

ISSN号： 0953-8984

摘要： The microscopic mechanism for H and He trapping by vacancy defects and bubble formation in a Be host lattice is investigated using first-principles calculations. A single He atom prefers to occupy a vacancy centre while H does not. He can segregate towards the vacancy from the interstitial site much more easily than H. Both H and He exhibit lower diffusion barriers from a remote interstitial to a vacancy with regard to their diffusion barriers inside a perfect Be solid. Up to five H or 12 He atoms can be accommodated into the monovacancy space, and the Be-He interaction is much weaker than Be-H. The physical origin for aggregation of multiple H or He atoms in a vacancy is further discussed. The strong tendency of H and He trapping at vacancies provides an explanation for why H and He bubbles were experimentally observed at vacancy defects in materials. We therefore argue that vacancies provide a primary nucleation site for bubbles of H and He gases inside Be materials.